[英]Can't get inside my for loop (Javascript)
我正在尝试遍历可变pieces
,但是不知何故,它不会触发。 在下面的函数中, pieces.length
变为4,但是piecesNew
变为[]
-而且从未到达console.log(i)
。
怎么了?
self.reworkPieces = function(pieces) {
var piecesNew = [];
console.log(pieces.length)
for (var i; i <= pieces.length; i++) {
console.log(i)
piecesNew[i] = {
c: pieces[i].r,
r: pieces[i].c,
p: i
}
}
console.log(piecesNew)
return piecesNew;
};
undefined
不小于或大于任何数字。
var i; // undefined
i < 10; // false
i > 10; // false
您只需要确保i
等于0
。
您还希望i
永远不等于pieces.length
所以请使用<
而不是<=
(数组的最后一个索引始终为length - 1
,例如,长度为3的数组具有索引0、1和2 –第一个索引为始终为0,而不是1)
所以:
for (var i = 0; i < pieces.length; i++) {
...
定义变量i的值, var i = 0
self.reworkPieces = function(pieces) {
var piecesNew = [];
console.log(pieces.length)
for (var i = 0; i <= pieces.length; i++) {
console.log(i)
piecesNew[i] = {
c: pieces[i].r,
r: pieces[i].c,
p: i
}
}
console.log(piecesNew)
return piecesNew;
};
self.reworkPieces = function(pieces) {
var piecesNew = [];
console.log(pieces.length)
for (var i = 0; i <= pieces.length; i++) {
console.log(i)
piecesNew[i] = {
c: pieces[i].r,
r: pieces[i].c,
p: i
}
}
console.log(piecesNew)
return piecesNew;
};
更改:
for (var i; i <= pieces.length; i++)
至:
for (var i = 0; i < pieces.length; i++)
首先初始化var i = 0,然后它将起作用
self.reworkPieces = function(pieces) {
var piecesNew = [];
console.log(pieces.length)
for (var i = 0; i <= pieces.length - 1; i++) {
console.log(i)
piecesNew[i] = {
c: pieces[i].r,
r: pieces[i].c,
p: i
}
}
console.log(piecesNew)
return piecesNew;
};
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